1. Field of the Invention
The present invention relates to a device for controlling a multi-cylinder engine.
2. Description of the Related Art
There is known an internal combustion engine wherein the fuel injection system, the ignition system, the idling speed control system, and other systems are controlled based on the outputs of a pair of digital computers and provision is made of switching means for selectively inputting the outputs of the digital computers to the controlled systems (see Japanese Unexamined Patent Publication (Kokai) No. 61-49154). In this internal combustion engine, when the pair of digital computers are operating normally, the fuel injection system and the ignition system are controlled based on the output of one of the digital computers and the idling speed control system etc. are controlled based on the output of the other digital computer. When an abnormality occurs in one digital computer, all the systems are controlled by the other normally operating digital computer. In this way, even if an abnormality occurs in one digital computer, it is still possible to control the systems due to the provision of multiple digital computers.
In such an internal combustion engine, however, there is the problem that multiple controlled systems are themselves not provided, so when a controlled system malfunctions, the fuel injection for all the cylinders becomes impossible or the ignition of all the cylinders becomes impossible, so the engine cannot be operated.